THE INFLUENCE OF THE INTRALUMINAL INTESTINAL MILIEU ON ABSORPTION OF AN ORGANIC CATION AND AN ANIONIC AGENT

¹ Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts

Various agents, such as amino acids, bile and bile salts, hexose acids and sorbitol, had no effect on the in vivo absorption of benzomethamine, a quaternary ammonium drug. Hyaluronic acid, chondroitin sulfate, sodium metaphosphate, and calcium chloride significantly decreased the per cent of the onium absorbed from intestinal loops. Only the saturated water-soluble fatty acids, acetic, propionic and butyric, increased the absorption of benzomethamine. These acids had this facilitatory effect only when added to the medium in relatively high concentrations (0.2 M) and at relatively low pH. However, this increased absorption was shown not to be simply the result of an acidic intestinal environment or irreversible changes in the gut wall.

The in vivo absorption of phenol red was also investigated. A new simple method for the accurate determination of phenol red in tissue was developed and is described. Phenol red is absorbed to the extent of 7.1 ± S.D. 1.04%. Butyric acid, 0.2 M, pH 2.9, significantly increased the absorption of phenol red and again this was not merely the result of the acidic medium.